package com.zfl;

import java.util.Scanner;

public class Q2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long R = sc.nextLong();
        long r = sc.nextLong();
        double probability;
        if (R < r && r > 2 * R) {
            probability = 0.0;
        } else {
            double numerator = 2 * R * r - r * r;
            double denominator = R * R;
            probability = numerator / denominator;
        }
        System.out.printf("%.6f\n", probability);
    }
}
